This invention relates to the use of alkyl glycosides as emulsifiers in the polymerization of ethylenically unsaturated monomers. 2. Description of Related Art
Alkyl glycosides have been known for some time. Their production is described, for example, in U.S. Pat. No. 3,839,318; according to which the starting materials used are glucose or oligosaccharides on the one hand and C.sub.8 -C.sub.25 alcohols on the other hand. Alkyl glycosides have acquired commercial significance as surface-active agents, for example, in detergents. In addition, alkyl glycosides have also been proposed for various commercial applications. Thus, Applicants' earlier German Patent Application P No. 34 04 558.9 describes special aqueous lacquer resin dispersions in which alkyl glycosides are present as incorporable emulsifiers, i.e. emulsifiers which are co-crosslinked on stoving.
U.S. Pat. No. 3,340,243 describes a process for producing PVC by suspension polymerization in which the dispersant used consists of methyl glucoside dilaurate in addition to protective colloids. The methyl glucoside dilaurate is not an alkyl glycoside in the sense of the present invention.
Despite the numerous otherwise known compounds, alkyl glycosides have never been used in the field of emulsion polymerization. Hitherto, it has not been possible for those skilled in this art to draw firm conclusions from the chemical structure of a compound as to its suitability as a polymerization emulsifier. Accordingly, in view of the many requirements which polymer dispersions now have to satisfy, there is a continuing need for new polymerization emulsifiers. In this connection, the emulsifier used in the emulsion polymerization process has a crucial effect not only on the beginning and the subsequent course of the polymerization reaction, but also on the mechanical and chemical stability of the finished polymer emulsions (dispersions). Thus, such properties as, for example, frost stability and stability in storage depend crucially on the emulsifier.